/**
* DBSCAN-function expandCluster.
*
* <p>Border-Objects become members of the first possible cluster.
*
* @param relation Database relation to run on
* @param rangeQuery Range query to use
* @param startObjectID potential seed of a new potential cluster
* @param objprog the progress object for logging the current status
*/
protected void expandCluster(
Relation<O> relation,
RangeQuery<O> rangeQuery,
DBIDRef startObjectID,
FiniteProgress objprog,
IndefiniteProgress clusprog) {
DoubleDBIDList neighbors = rangeQuery.getRangeForDBID(startObjectID, epsilon);
ncounter += neighbors.size();
// startObject is no core-object
if (neighbors.size() < minpts) {
noise.add(startObjectID);
processedIDs.add(startObjectID);
if (objprog != null) {
objprog.incrementProcessed(LOG);
}
return;
}
ModifiableDBIDs currentCluster = DBIDUtil.newArray();
currentCluster.add(startObjectID);
processedIDs.add(startObjectID);
// try to expand the cluster
HashSetModifiableDBIDs seeds = DBIDUtil.newHashSet();
processNeighbors(neighbors.iter(), currentCluster, seeds);
DBIDVar o = DBIDUtil.newVar();
while (!seeds.isEmpty()) {
seeds.pop(o);
neighbors = rangeQuery.getRangeForDBID(o, epsilon);
ncounter += neighbors.size();
if (neighbors.size() >= minpts) {
processNeighbors(neighbors.iter(), currentCluster, seeds);
}
if (objprog != null) {
objprog.incrementProcessed(LOG);
}
}
resultList.add(currentCluster);
if (clusprog != null) {
clusprog.setProcessed(resultList.size(), LOG);
}
}
/**
* Process a single core point.
*
* @param neighbor Iterator over neighbors
* @param currentCluster Current cluster
* @param seeds Seed set
*/
private void processNeighbors(
DBIDIter neighbor, ModifiableDBIDs currentCluster, HashSetModifiableDBIDs seeds) {
for (; neighbor.valid(); neighbor.advance()) {
if (processedIDs.add(neighbor)) {
seeds.add(neighbor);
} else if (!noise.remove(neighbor)) {
continue;
}
currentCluster.add(neighbor);
}
}
